Field Trip Guide Book: Petroleum System of East Java Basin
Instructor: Awang H. Satyana
Years: 2015
Instructor: Awang H. Satyana
Years: 2015
REGIONAL GEOLOGY
East Java Basin in the southeastern margin of the Sundaland has recorded complicated tectonic, volcanic, stratigraphic, and structural evolution since the formation of the basin in the Eocene time until Quarternary time. The basin started in the middle Eocene time by rifted structures on complicated basement, considered as a response to subduction rollback to the south of East Java due to deccelaration of subduction rate related to far-field stress of India – Eurasia collision in 50 Ma. The basin has gained its tectonic setting as back-arc basin since the Eocene time. Like other sedimentary basins in Western Indonesia, during the Paleogene-Early Neogene the East Java Basin underwent extensional tectonics and structural styles due to rifting and sagging mechanisms.
STATIGRAPHY
Generalized stratigraphic correlation of East Java Basin (Ardhana, 1993) |
Smyth et al. (2005) subdivided East Java into four east-west trending zones based on the van Bemmelen (1949)’s physiographic zones. The zones are defined by stratigraphy and structure and, from south to north, are as follows.
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OUTCROP 1.1
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OUTCROP 2.1
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OUTCROP 2.2
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OUTCROP 3.1
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OUTCROP 4.1
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Quartz sandstones, sandy clay and orbitoidal limestones croppe out at Braholo river side cliff. The outcrop is part of Ngrayong Member of Tawun Fonnation. In Cepu area the quartz sandstone is a reservoir rock. The orbitoidal limestones contain fragmens and well preserved
molluscas and larger foraminifera (Lepidocyclina and cycloclypera). |
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